Computer systems providing large-scale data storage service to host computers have been provided. Such system is known to include a host computer, a storage subsystem to which the host computer connects, and a management device of the storage subsystem. The storage subsystem manages a plurality of hard disks via RAID (Redundant Array of Independent/Inexpensive Disks) configuration. The system logicalizes physical storage areas included in a plurality of hard disks, and provides them to the host computer as logical volumes. The host computer accesses the logical volumes and requests reading and writing of data.
As a recent technical trend, there are demand for downsizing the storage subsystem space, cutting down operation management costs, facilitating maintenance, and efficiently utilizing CPU and other resources. Along therewith, a unified storage system, which is an integrated storage subsystem capable of corresponding to a plurality of protocols such as FC (Fibre Channel), iSCSI, FCoE (Fibre Channel over Ethernet) and NAS (Network Attached Storage) via a single machine, is attracting attention. The merits of an integrated machine are that it enables direct connection of elements, suppresses development costs, and ensures performance.
Moreover, an art of logically dividing hardware resources included in a storage system connected to a network and receiving file accesses (such as a NAS), and independently operating the individual logical partitions (virtual storage subsystems) is known (refer to patent literature 1).